Pika

Literally every animal character in the movies (except Shadow) is from another planet. Just make Blaze from another world and boom.

Plus, Shadow is probably the sonic character with the most amount of lore in the franchise (in my opinion) yet he still appeared in the movies. Blaze is pretty likely to appear in the movies if silver appears.

Elise, Sticks, and Gamma I can agree with. I don't see them happening, and Sega probably wants to distance themselves from 06 as much as possible. Tikal, it depends on if Chaos appears and what his origins end up being. If he ends up being just like his game counterpart, or if they make him one of eggman's creations or something.

Infinite is probably the second most likely to appear in this whole list. He could be a good villain for either a spinoff or a mainline movie. They have a chance to do infinite, who I think is a character with lots of potential, justice in the movies